Couch roll structure for paper making machines



Sept. 23, 1958 A. w. WESTERN ET AL 2,852,936

COUCH ROLL STRUCTURE FOR PAPER MAKING MACHINES 3 SheetsSheet 1 FiledJune 22. 1953 Inventors Amnun WILL-IAN WESTERN We L-rsn T y flaw f AYLOn1 Aitorney Sept. 23, 1958 2,852,986

COUCH ROLL STRUCTURE FOR PAPER MAKING MACHINES A. W. WESTERN ET AL 5Sheets-Sheet 2 Filed June 22. 1953 1 n uentors ESTE N ZYLO M ARTHURWILLIAM w W4 LTER A ttorney p 1958 A. w. WESTERN ET AL 86 COUCH ROLL.STRUCTURE FOR PAPER MAKING MACHINES Filed June 22. 1953 3 Sheets-Shem; 5

IN VENTOR.

firihw willie! Wasfim BY Walkr Tqqlor .4 TTGKNEYS United States PatentCOUCH ROLL STRUCTURE FOR PAPER MAKING MACHINES Arthur William Westernand Walter Taylor, Greenhithe, England, assignors to Empire Paper MillsLimited, Greenhithe, England, a British company Application June 22,1953, Serial No. 363,188

. Claims priority, application Great Britain June 26, 1952 16 Claims.(Cl. 92-47) This invention relates to improvements in or relating topaper-making machines, and more particularly to devices for supervisingthe position of draw of the wet paper web from the forming belt or wire.

In conventional paper-making machines, it is usual to provide a suctioncouch roll around which the forming belt or wire passes, the wet paperweb being drawn ofi this couch roll on to a press roll whereafter it isdried in a known manner. The position at which the newly formed wetpaper web leaves the forming belt is known asthe position of draw andthe actual draw position of the-web in relation to the couch roll iscritical, if the drawocc urs too early, while the web is still over thesuction box within the couch roll, the effect known as plucking isproduced, i. e. the portions of the web in register with theperforations of the couch roll are held back by the suction, and if thedraw is too late the web tends to run down the couch roll and break. Inthe first event the quality of the paper produced by the machine isimpaired and in the latter event machine stoppages due to web breakageoccur with excessive frequency. It will be appreciated that the correctdraw position may well vary on a given paper machine according to theparticular grade or typeof paper being made.

' It is an object of the present invention to provide a supervisorydevice whereby a continuous indication of the position of draw may begiven so that deviations in either sense or in both senses areimmediately made known.

According to the invention therefore, there is provided a supervisorydevice for indicating the position of draw of a wet paper web,comprising a chamber adapted to be maintained at low pressure, and tocommunicate with the interior surface of a suction couch roll at adetecting position in the region of the required position of draw,whereby in operation air may be admitted to said chamber whenever thecouch roll at said detecting position is not "covered by the paper web,and pressure-responsive means associated with said .chamber.

The said chamber may be formed integrally with the suction box of asuction couch roll for example by adaptation of that portion of thesuction box which carries the sealing strip at the trailing edge of thevacuum box. We prefer however to provide a separate chamber which isadapted to be mounted on a convenient part of the suction box e. g. thewall thereof at the trailing side, and to make communication with theinterior surface of the couch roll either through the sealing strip atthe trailing edge of the suction box or viapassage means associated withthe chamber, dependent upon whether the desired detecting position lieswithin the width of the sealing strip of the suction box or forwardlythereof in the direction of travel of the paper web.

In one form of the invention the said chamber is provided with aconnection to the interior of the normal suction box to produce thedesired low pressure in the chamber. However, it is preferred to omitsuch a connection as it is normally possible for the device to operatemerely by the pressure reduction produced by the pumping action of n ICCthe couch roll perforations. As the latter leave the region above thesuction box, they are normally covered by the wet paper web and are at asub-atmospheric pressure as a result of the vacuum provided by thesuction box. If they are immediately placed in communication with thechamber, the latter will become progressively exhausted until it reachesa pressure nearly as low as that in the suction box.

If now the draw occurs before the detecting position, no reducedpressure can be established in the chamber while if it occurs after thedetecting position, a steady low pressure will be maintained. In thecase where the web leaves the roll at the detecting position, a pressurefluctuation may be established.

The said pressure-responsive means may take various forms but we preferto employ a diaphragm-operated electric switch which may be connected incircuit with any desired lamps, bells, buzzers or other warning devices.Such a switch may be situated in a wall of the chamber itself, or may beremote therefrom and connected thereto by suitable piping. It isdesirable that the switch or other pressure-responsive means should beable to respond to the pressure fluctuations which may be establishedwhen draw takes place at the detecting position, so that with anindicating lamp for example a flickering light is obtained. Then if thedetecting position is the desired draw position, a flickering light willindicate correct operation, while a light extinguished or steadilyburning indicates a high or low draw (or vice versa, according to theswitch response).

Where a draw position anywhere within a given range is satisfactory, twodetecting position may be used each with its associated chamber andpressure-responsive means, and the latter may be interconnected to giveno indication when the one chamber is at low pressure while the other isat atmospheric pressure, but to give visual or aural signals when thecondition of either chamber changes.

Normally an attendant will be present to correct the draw by suitableadjustments of the machine upon an adverse indication being given by thedevice according to the invention, but it is within the scope of theinvention to connect the device to control means for the machine to makeautomatic correction, e. g. by varying the speed of the couch roll and/or regulating a stock inlet valve.

It is to be noted here that if due to opening of the stock inlet valvethe substance weight increases the draw of the web from the couch rollwill occur earlier since the added strength of the wet web more thancounteracts the increased weight and there is less sag in the webbetween the couch roll and the press roll. Conversely if the substanceweight decreases then the draw will occur later. Thus where correctionsin response to the device are to be made by regulation of the stockinlet valve, the control means will be so connected with the said valveand the device as to take these factors into account.

The chamber may be maintained in communication with the interior surfaceof the couch roll by various means: for many grades of paper the desiredposition of draw will be within the width of the trailing edge of thesuction box and it is then convenient to provide a bore through therubber sealing strip bounding the suction box. Where a single machinemay be operated at different times with various draw positions, a numberof such bores may be provided at correspondingly different angularpositions relative to the couch roll, and means may be provided forselectively employing different bores as required. valves whereby anyone of the bores may be connected to a single chamber, or each may haveits own chamber and the various chambers may be selectively connectibleto a single pressure-responsive means. Where the couch It may beconvenient to fit fluid roll has perforations in staggered rows, two ormore bores may be employed for each angular position to avoid deadspots. Alternatively, a slot may be provided inplace of such two or morebores, the length of the slot being suificient to cover the distance bywhich the perforations in successive rows of the couch roll arestaggered.

It is often valuable to make a continuous record of the draw position,and for this purpose devices embodying the present invention may includea vacuum recording gauge connected to the chamber. This has been foundto provide a record of considerable value, as apart from affording ameans of verifying an operators alertness and competence in correctingdraw variations, by comparison with other records, e. g. of the speed ofthe couch roll, changes in the various factors governing the drawposition can be analysed.

In order that the invention may be fully understood, preferredembodiments thereof will now be described, by way of example only,referring to the accompanying drawings, in which:

Figure 1 shows an end section through a suction couch roll incorporatinga device according to the invention,

Figure 2 is a side elevation of part of the couch roll of Figure 1broken away to show the mounting of the said device.

Figure 3 shows in vertical section and to an enlarged scale a preferredform of device according to the invention,

Figure 4 shows a similar view of part of a modified form of device,

Figure 5 shows a similar view of yet another form of device, and

Figures 6 and 7 are similar to Figure 2 but, respectively, show furthermodifications of the invention.

Referring first to Figures 1, 2 and 3, a paper-making machine includes aforming belt or wire 1 upon which a paper web 2 is continuously formed,said web 2 leaving the belt 1 at a draw position 3, to proceed to dryingrolls of which one felt roll 19 only is shown. Below the belt 1 at thedraw position 3 is a suction couch roll 4 having a suction box 5therein. A casting bolted to the wall on the trailing side of thesuction box 5 encloses a chamber 6 which is connected by a drilling 8 toa space below the rubber sealing strip 9 at the trailing edge of thesuction box 5. Two laterally spaced bores 10 (see Figure 2) through thestrip 9 and its backing 9a make communication between the chamber 6 andthe inner surface of the roll 4.

The chamber 6 is also connected, by a pipe 11, which extends out throughthe end of the couch roll 4, to a diaphragm type pressure-responsiveelectric switch 12. Chamber 6 is also connected, through pipe 11, to avacuum recording gauge G, shown schematically in Figure 3. The switch 12has its contacts 13 connected in series with a warning lamp 14 across alow-voltage supply 15, the contacts 13 being held open and the lamp 14thus remaining unlit whenever a sufliciently low pressure exists in thechamber 6. The diaphragm of the switch 12 is provided with a biasingspring 16 having an adjusting screw 17, so that the pressure required tohold the switch open may be set to a desired value. The said switch 12,lamp 14 and low voltage supply are all preferably mounted clear of thecouch roll 4 on any convenient panel.

The surface of the couch roll 4 has as is known, a plurality ofperforations 18 through which suction is applied to the wet web betweenthe leading and trailing edges of the suction box 5. It will be observed(Fig. 2) that the perforations 18 aredisposed in staggered rows,

' and one bore 10 is aligned with an even row while the other bore 10 isaligned with an odd row. As these perforations move past the trailingedge of the suction box 5 they will normally be at sub-atmosphericpressure due to the suction effect of the suction box and to the factthat they are covered by the web up to the draw off point. This lowpressure will therefore exercise a pumping effect on the chamber 6 viabores 10 and drilling 8 and will reduce the pressure in chamber 6, thetwo bores 10 operating alternately so that dead spots, when the chamber6 is blanked off by the roll, are substantially eliminated.

When the machine is in operation, if the paper web remains on theforming belt 1 until it has passed the trailing edge of the suction box,then the bores 10 have no access to the atmospheric air at their outerends and the chamber 6 is maintained at the reduced pressure mentionedabove. When however, the web leaves the belt before passing over thetrailing edge, then the bores 10 are opened to the atmosphere andpressure in the chamber 6 rises to atmospheric whenever a perforation 18of the couch roll passes a bore 10. The diaphragm of the switch 12 isadjusted so that, in the former case, its contacts are open while in thelatter case they are closed, the lamp 14 being respectively unlit andlit. If now the paper web leaves the belt just above the bores 10, thechamber 6 will be open to the atmosphere for a very short time, througha restricted opening, each time a perforation 18 passes, and a cyclicalpressure fluctuation is established which with a suitable adjustment ofthe switch diaphragm gives repeated opening and closing of the switchcontacts 13, and hence the lamp 14 flickers.

Thus, by locating the bores 10 so that they lie atthe required positionof draw or within a permitted region of draw it will be seen that whenthe lamp 15 is flickering the draw is correct whilst when it is steadilylit or unlit the draw is either too high or too low.

In a modified form of chamber shown in Figure 4 an additional drilling 7is provided which connects the inside of the chamber 6 to the interiorof the suction box and thus provides a low pressure which iscommunicated to the bores 10.

It will be understood that the detecting position as represented bybores 10 in Figures 3 and 4 may be varied within the width of thesealing strip as may be required on any given paper machine. If howevera detecting position outside the Width of the sealing strip is requireda device as shown in Figure 5 may be provided. The couch roll 4 has asuction box 5 with a sealing strip 9 at its trailing edge. Chamber 6 isbolted'to the wall of the suction box. It is in contact with the innerside of the couch roll 4 via an upper wall 20 having a seal ing strip 21therealong a perforation or drilling 22 connecting the interior of thechamber to the inner end of the perforations 18 of the couch roll 4. Thesaid chamber is similarly connected to pressure-responsive means as havebeen described above and the device operates in an analogous mannerthereto, the chamber being maintained at low pressure by the pumpingaction of the couch roll perforations 18 referred to with reference toFigure 3.

In any of the above described devices, the pipe 11 may be of any desiredlength, within reason, so that the switch 12 may be installed in anyconvenientposition remote from the chamber 5 and said pipe 11 may ifdesired extend through the open end of the couch roll.

In Figure 6 a modified couch roll according to the invention is shown.On the trailing side of the suction box 5 two chambers 6 and 6a aremounted. Each of these chambers 6, 6a is similar to chamber 6 abovedescribed. The sealing strip 9 of the suction box has two pairs oflaterally spaced bores 10, and 1011, which communicate, respectively,with chambers 6 and 6a. As shown, bores 10, and 10a are located,respectively, near the front and rear sides of the said strip 9 so thatthey define two detecting positions spaced circumferentially of thecouch roll. Chambers 6, and 6a are connected by pipes 11, 11a to a valvemeans shown schematically at 24, which enables either chamber to beselectively connected via pipe 11b to the common pressure responassgessa sive switch 12 depending upon which draw position is to be used.

In Figure 7 a further modified construction is shown in which a singlechamber 6c is mounted on the trailing side of the suction box 5. l'hesealing strip 9 has tWO pairs of bores 10, 10a therethrough each ofwhich communicates with the said chamber 60. Valve means 23 are providedfor each pair of bores, 10 and 10a, respectively, which enable eitherone of said pairs of bores 10, 10a to be selectively disconnected fromchamber 6 whilst the other is connected therewith. The two pairs ofbores '10-, and 10a are located respectively near the front and rearsides of the sealing strip 9 so that they are circumferentially spacedwith respect to the couch roll. Hence by closing one of the valves 23the chamber 6 can be placed in communication with a selected one of twodetecting positions provided by bores 10 and 10a depending upon whichposition of draw is required.

It will be understood that only preferred embodiments of the inventionhave been described above by way of example and that variations andmodifications may be made therein without departing from the scope ofthe invention. Thus for instance two lamps or other warning devices maybe connected to a source of current through the pressure responsivedevice, so that when one warning device is operated an indication of ahigh draw is given whilst the other Warning device indicates a low draw,the draw being correct when neither warning device is operating.

What we claim is:

1. In a suction couch roll for a paper making machine which rollincludes a perforated shell and a suction box having an open sideagainst the inner surface of said roll and extending a relatively largecircumferential distance therein, said machine including means fordrawing a paper web from said roll substantially tangent to said roll ata predetermined circumferential position, the improvement constituting aweb-detecting device which comprises; means defining a chamber, meansdefining a passageway providing direct communication between saidchamber and the interior surface of said shell at said predeterminedcircumferential position of small circumferential extent locatedadjacent but spaced from the trailing edge of said suction box, andpressure responsive indicating means controlled by pressure in saidchamber, whereby in operationatmospheric air is admitted to said chamberwhenever said paper web is drawn from said roll in advance of saidpredetermined position.

2. A suction couch roll as set forth in claim 1 including a sealingstrip between the trailing edge of said suction box and the innerperiphery of said shell, and means defining a radial opening throughsaid sealing strip on the trailing side of said suction box and definingat least a portion of said passageway.

3. A suction couch roll as set forth in claim 1 in which said pressureresponsive means is a diaphragm-operated electric switch connected bypipe means to said chamber.

4. A suction couch roll as set forth in claim 1 in which a vacuumrecording device is connected to said chamber to record variations inpressure occurring therein in operation.

5. In a suction couch roll for a paper making machine which rollincludes a perforated shell and a suction box having an open sideagainst the inner surface of said roll and extending a relatively largecircumferential distance therein, said machine including means fordrawing a paper web from said roll substantially tangent to said roll ata predetermined circumferential position, the improvement constituting aweb-detecting device which comprises; means defining a chamber, meansdefining a passage on the trailing side of said suction box providingdirect communication between said chamber and the interior surface ofsaid shell at said predetermined circumferential position, meansdefining a further passaid pressure responsive means is adiaphragm-operated electric switch connected by pipe means to saidchamber.

8. A suction couch roll as set forth in claim 5 in which a vacuumrecording device is connected to said chamber to record variations inpressure occurring therein in operation.

9. In a suction couch roll for a paper making machine which rollincludes a perforated shell and a suction box having an open sideagainst the inner surface of said roll and extending a relatively largecircumferential distance therein, said machine including means fordrawing a paper web from said roll substantially tangent to said roll ata predetermined circumferential position, the,

improvement constituting a web-detecting device which comprises; meansdefining a chamber on the trailing side of said suction box, saidchamber having a wall in contact with the inner surface of said shell,means defining a passage through said Wall providing directcommunication between said chamber and the said inner surface at saidpredetermined circumferential position, and pressure responsive meanscontrolled by pressure in said chamber, whereby in operation air isadmitted to said chamber whenever said paper web is drawn from said rollin advance of said predetermined position.

10. A suction couch roll as set forth in claim 9 including meansdefining a further passage connecting said chamber to the interior ofsaid suction box.

11. A suction couch roll as set forth in claim 9 in which said pressureresponsive means is a diaphragmoperated electric switch connected bypipe means to said chamber.

12. A suction couch roll as set forth in claim 9 in which a vacuumrecording device is connected to said chamber to record variations inpressure occurring therein in operation.

13. In a suction couch roll for a paper making machine which rollincludes a perforated shell and a suction box having an open sideagainst the inner surface of said roll and extending a relatively largecircumferential distance therein, said machine including means fordrawing a paper web from said roll substantially tangent to said roll ata predetermined circumferential position, the improvement constituting aweb-detecting device which comprises; means defining a chamber, meansdefining at least two passages at the trailing side of said suction box,said passages being circumferentially spaced, with respect to the shelland each providing direct communication between said chamber and theinterior surface of said shell at different detecting positions adjacentto but respectively ahead of and rearwardly of said predeterminedposition, pressure responsive means controlled by pressure in saidchamber, and valve means for selectively disconnecting all but one ofsaid passages from said chamber whereby in operation air is admitted tosaid chamber whenever said selected passage is not covered by paper.

14. A suction couch roll as set forth in claim 13, including sealingstrips between said suction box and said shell, said spaced passagemeans being formed in said sealing strip on the trailing side of saidsuction box.

15. A suction couch roll for a paper making machine comprising aperforated shell, a suction box having an open side against the innersurface of said roll and extending a relatively large circumferentialdistance therein,

said machine including means for drawing a paper web from said rollsubstantially tangent to said roll at a predetermined circumferentialposition, means defining at least two chambers, each chamber havingpassage defining means at the trailing side of said suction boxproviding direct communication between its respective chamber and theinterior surface of said shell at detecting positions adjacent to butrespectively ahead of and rearwardly of said predetermined position therespective passage defining means being circumferentially spaced withrespect to said shell, pressure responsive means, and valve means forselectively connecting one of said chambars to said pressure responsivemeans whereby in operation air is admitted to said one chamber toactuate said pressure responsive means whenever said shell at thedetecting position associated with said one chamber is not covered bythe paper web.

16. A suction couch roll as set forth in claim 15 including sealingstrips between said suction box and said shell, said respective passagedefining means being in said sealing strip at the trailing side of saidsuction box.

References Cited in the file of this patent UNITED STATES PATENTS1,508,138 Foote Sept. 9, 1924 1,581,656 Monaghan Apr. 20, 1926 1,933,814Lewellen et al Nov. 7, 1933 2,107,812 Berry et al. Feb. 8, 19382,338,465 Street Jan. 4, 1944 2,338,777 Millspaugh J an. 11, 19442,714,342 Beachler Aug. 2, 1955

